The objective of the proposed project is to study the basal ganglia. More specifically, we intend to study the intrinsic organization of the striatum, extrinsic inputs from the cerebral cortex, thalamus and the substantia nigra, the striatial projection neurons and their effect on the target neurons in the globus pallidus and the substantia nigra, and the projection neurons in the globus pallidus and the substantia nigra. Techniques utilized are intracellular recording, intracellular injection of HRP, light and electronmicroscopic examination of the intracellularly injected neurons with HRP and fluorescent catecholomine histochemistry for identification of HRP injected neurons. Rats and cats will be used as experimental subjects.